EPS is an ideal choice for green building designs, offering tangible environmental advantages with energy efficiency, recycled content, mold resistance and indoor environmental quality.
EPS can help meet other green building goals via localized manufacturing, which reduces the impacts of transportation and through its use in innovative applications that improve the overall environmental performance of the building envelope. During installation, some EPS applications have shown to consistently reduce jobsite waste and labor costs. And, once installed, the environmental benefits continue with superior insulating properties that result in measurable savings.
Beyond the environmental benefits of the installed product, the energy requirements to make polystyrene can be more favorable than some alternative materials. In one study, when compared to fiberglass insulation, the energy required to produce polystyrene foam insulation is 24 percent less than what is needed to make the amount of fiberglass needed to achieve an equivalent R-value at a representative volume.
EPS foam insulation can contribute toward green building recognition in a variety of point or credit categories including energy efficiency, recycled content, localized distribution, indoor air quality, sustainable sites and innovation. Several structural system applications, like insulating concrete forms (ICFs) and Structural Insulation Panels (SIPS) that use EPS are commonly recognized by LEED and other green building guidelines as providing key environmental advantages.
For maximum energy efficiency, EPS rigid foam insulation can be specified to achieve the desired thermal resistance and can significantly reduce air leakage that may occur in roof, wall and below grade assemblies. The amount of insulation required will vary depending on the building design, climate and energy costs, making it important to choose the most cost effective R-value per inch.
EPS delivers R-value ranging from 3.60 to 4.20 per inch. It is the only rigid foam insulation that offers stable thermal resistance from the point of manufacture. Foam insulation is effective in buildings with space limitations and where higher R-values are needed. EPS rated at R-4 per inch of thickness can provide up to two times greater insulation than traditional insulating materials of the same thickness.
Other rigid foam insulation materials require testing to determine their long-term thermal resistance (LTTR) which can add to product development costs and render a calculated ‘guess’ at the insulation’s performance over time. EPS does not have to conduct such tests because it does not experience thermal drift, meaning its R-value remains constant throughout the life of the building.
While all insulation is inherently green due to its energy savings capabilities, green attributes will differ based on each material’s physical properties and its subsequent ability to enhance sustainability.
Most significantly, whether used as a stand alone component or part of a highly engineered building system, EPS’ insulating capabilities contribute to increased energy efficiency. Whether for sheathing, roofing or below-grade installations, EPS plays a key role in a building’s ability to comply with ASHRAE 90.1 – 2001, a benchmark requirement for most green building programs.
EPS Slab-On-Grade floors is one example that demonstrates energy savings. According to the U.S. Department of Energy (DOE), Office of Building Technology, insulating the exterior edge of the foundation slab can reduce winter heating bills by up to 10 to 20 percent. An insulated slab also provides thermal mass to store heat and moderates indoor temperatures.
Studies designed to evaluate newer building systems applications, like structural insulated panels (SIPS) and insulated concrete forms (ICFs) have shown increased energy savings over competing materials, up to 25 percent. In a 1993 test conducted by the Florida Solar Energy Center, a building constructed with EPS insulation tested at only 1.8 air changes per hour (ach) versus 3.9 ach measured for a conventional, stick frame construction. Similar results for ICFs made using EPS are shown in a study performed by Oak Ridge National Laboratory, “Dynamic Thermal Performance and Air-Tightness Effects of Concrete and Masonry Walls” and the Department of Housing and Urban Development, “Insulating Concrete Forms: Installed Cost and Acoustic Performance.” Houses built with ICF exterior walls require an estimated 44 percent less energy to heat and 32 percent less energy to cool than comparable frame houses.
When properly installed, EPS insulation reduces the transfer of heat flow, either out of or into the building. Structural systems like SIPs and ICFs further improve the resistance to heat flow by providing tighter construction. Additional studies from the Cement Association of Canada (CAC) and the Northwest Territories Housing Corp. (NWTHC) show that homes constructed with ICFs above and below grade wall construction have reduced air infiltration compared to other wall assemblies.